Energy is a liquid substance found in the Game Grid and the Tron system, used as a fuel for vehicles and as a vital nourishment for all programs. Energy acts and behaves like water and food from the real world, and is essential to programs just like food and drink are essential to us in the real world. If a program does not have enough energy, he or she may derez.

Digitized users can also consume energy and use it to help restore broken vehicles or even save a life of a program by transferring the energy to a person or object. While in cyberspace for the first time, Kevin Flynn transferred his energy to restore power to a formerly broken recognizer. When Ram noticed this he claimed that such a function was impossible for a program to do. Flynn also saved Yori's life by transferring some his energy to her before she derezzed.

Sam and Castor drink energy at the End of Line Club.

Energy is usually found in rural parts of cyberspace, especially in caves and canyons. Flynn's first encounter with energy was in a cave, shortly after escaping the game grid with Ram and Tron. When Flynn asked what it was, Ram replied "Just what I need, right now". Flynn noticed that when Tron and Ram were drinking the liquid, their circuitry glowed brightly, denoting that they were regaining energy.

Refined energy is sold at locations including End of Line Club, sometimes as energy drinks. Whether it's more potent or possibly flavored remains unknown.
In TRON 2.0, energy patch routines make an appearance. A player can walk up to the patch routine and activate it to download energy. There are two types of energy patch routines: green patch routines give a limited amount of energy (usually about 100 points of energy), whereas light blue patch routines give an unlimited amount of energy. Because light blue patches are less common, they are harder to find than light green energy patches. In TRON 2.0 there are also some energy pools which give unlimited energy, but slowly than a patch routine.

Energy in TRON 2.0 does a few extra things: it allows the player to fire any weapon other than the Identity Disc; downloads permission, subroutines, or e-mails; or activates some doors and switches. The player's maximum allowed energy may be increased by going up a version number.

In TRON: Evolution, Anon can regain health energy by running across Energy Transfer Conduits (ETCs), glowing strips that are on walls. He can obtain energy for special attacks by vaulting across energy pods and consoles.